This invention relates to a process for supply of biologically active materials to base material, such as processed foodstuff and feed, and especially to such a process where low concentrations, preferably of the order of parts per million of biologically active materials are supplied to the base material.
It is known that ever more foodstuffs and feed are subjected to processes, by the purpose of which is to improve the nutrient properties, taste, structure, handling ability etc. of the foodstuff and feed. Most of these processes utilize heat, pressure, grinding and other physical working often in combination with supply of steam or another form of heat. Examples of such processes are rolling, steam boiling, extrusion, pelletizing etc.
For the purposes of this description the expression "base material" concerns foodstuffs and feed that have been subjected to the processes described above.
It is also known that certain sensitive nutrients such as vitamins, enzymes and recently also living bacteria which are intended to be supplied to a base material, do not withstand certain steps in the processes described above but are destroyed or, in any case, lose their so-called biopotency completely or partly.
One way of trying to avoid a decrease in the biopotency of the biologically active material or denaturation of the material is described in Swedish patent application 7902104-4, where bacteria are encapsulated in for example fats or the like. The material thus encapsulated, for example admixed to animal food, withstands for instance pelletizing better than materials not being encapsulated.
One way of avoiding the problem of denaturation should be to supply biologically active material to a processed feed or foodstuff, i.e. to the base material. However, such a process involves considerable technical difficulties. For instance, one difficulty may be that the biologically active material, the amount of which is small relative to the base material, cannot be evenly distributed therein. Another problem is that the even admixture is not very likely to remain homogeneous, even if one should be successful in mixing a small amount of biological material homogeneously with a large amount of base material, but with all probability the material will be stratified in a subsequent handling. Still a problem in connection with an admixture of biologically active material in foodstuffs or animal food is the known phenomenon of friction between the particles to be homogenized. A slow and careful homogenization usually results in a bad homogenity while an efficient homogenization destroys biologically active material completely or partly.
One method of reducing the risks of a similar reduction of the bioactivity is using for example encapsulated material, as mentioned above. However, the homogenity problem cannot be solved by this method, particularly not as the density and the particles size of the materials to be mixed differ from each other.
A way of solving the problem with a homogeneous and constant admixture of material in for example seed is described in Swedish application No. 7904283-4, where a finely divided material to be supplied to seed or grain for instance is mixed with e.g. oil or fat to form a paste which is sorbed by the seed. However, the method implies synergistic components of the mixture with respect to sorption of the seed; moreover, relatively large amounts of additives are required for a homogeneous admixture.
As certain biologically active materials are active also in amounts of the order of parts per million, the method is not useable for supply of such materials. Another disadvantage of the method is that the carrier used together with finely divided material is supplied in small amounts which, therefore, cannot possibly protect biologically active materials from physical and chemical effects or contribute to a homogeneous admixture, especially as small amounts of active material are to be bonded to the seed.
Certain biologically active materials are sensitive to moisture. Examples of this are certain freeze-dried bacteria concentrates. As one has recently started to use living bacteria for admixture in for example dry feed or dry foodstuff an increased demand is made on the stability of these active materials against for instance moisture. One way of increasing the resistance to moisture of the active material, e.g. the moisture resistance of freeze-dried bacteria, is for instance described in CH A 525 957, according to which a freeze-dried bacteria mass is mixed with oils or fats to form a paste which will then have a certain protection.
However, it is known that a homogeneous admixture of such a paste in feed or foodstuff implies a relatively large amount of bacteria paste, probably 5-10% or more. Otherwise the homogenization must be so effective that the survival of the bacteria is put at risk while the structural properties of the material can be changed.
It is apparent from the above-mentioned description of prior art that none of the methods described therein is suitable to utilize when it is desired to add small amounts of biologically active materials to base materials, i.e. processed feed or foodstuffs, in such a way that the biologically active material is distributed homogeneously, on the one hand, and the active material, on the other hand, is protected at the same time against mechanical and other physical strains such as mixture, transport and storage.